The present invention relates to a card reader and in particular a card reader of reduced dimensions.
Currently one of the drivers in the radio telephone market is phone size and it is desirable to reduce phone size. Over recent years there has been considerable success in reducing the length and width of a radio telephone. Although the depth of radio telephone has been reduced, it has been found that it is more difficult to reduce phone size in this dimension compared to other dimensions. This may result in aesthetically unappealing phone shapes.
Accordingly it would be desirable to reduce the size of a radio telephone along its depth dimension.
A typical radio telephone has a vast number of components. In the smaller radio telephones such as the NOKIA 8810 (Trade Mark) the phone has been carefully optimised to minimise weight and size. The innovation which underlies the present application results in part from the inventor's realisation that the SIM card reader, which is ostensibly optimally designed for space reduction, is one part of the radio telephone in which, with ingenuity, volume could be saved.
FIGS. 1 and 2 illustrate a current SIM card reader 2. The SIM card reader 2 receives a SIM card 50 that has a card substrate 52 on which there is a plurality of separate conductive contact portions 54. The reader 2 has an interconnect 30 each of which connects a contact portion 54 of the SIM card to a radio telephone printed circuit board 10 via a connect 36. The interconnect 30 has a cantilevered portion 34 which is firmly held between an upper substrate 40 and a lower substrate 20 of the card reader 2 and a curved contact portion 32 for connecting with the a contact portion 54 of the SIM card. The lower substrate 20 has a recess 22 position beneath the curved contact portion 32 of the interconnect 30. This recess 22 has a clearance or depth 24. The upper substrate 40 has a catch or clamp 42 which defines an abutting surface 44 which overhangs a parallel restraining portion 46 of the upper substrate 40. The gap between the abutting surface 44 of the catch 42 and the restraining surface is slightly greater than the thickness of a SIM card.
The SIM card 52 is placed into the card reader 2 by lowering the card 52 so that it abuts with the curved contact portion 34 of the interconnect 30 and flexes the interconnect and then sliding the card so that it nestles underneath the abutting surface 44. Releasing the card results in it being held between the upward force provided by the flexed interconnect 30 and the restraining reaction provided by the abutting surface 44. When the card is in position the cantilevered portion 34 of the interconnect is flexed downward and the curved portion 32 moves into the recess 22. The cantilevering of the interconnect 30 between the restraining portion 46 of the upper substrate and the lower substrate allows the resilient interconnect to return to its quiescent position standing proud of the restraining surface 46 when the card is removed. It is important that the SIM card can be easily removed and returned to the reader without any tools.
Further SIM card readers according to the prior art are described in U.S. Pat. No. 5,718,609 and U.S. Pat. No. 5,320,552.
These SIM card readers also use resiliently flexible interconnects to connect to the SIM card. Such interconnects in SIM card readers are reliable and up until now there has been no motivation to adapt them.
The inventor identified that the resiliently flexible interconnect provides the dual function of connecting the SIM card to the PCB and providing a sprung contact holding the SIM card in position. He realized that one feature limiting the reduction of the size of the card reader was that enough room must be provided in the SIM card reader to allow the recess 22 to accept the resilient interconnect when it flexes downwards on inserting the SIM card. The inventor after having successfully identified where volume might be saved additionally realized how this saving may be effected by the novel application of known technology to provide both a low volume and reliable contact.
This known technology includes U.S. Pat. No. 4,125,310, U.S. Pat. No. 5,197,184 and U.S. Pat. No. 5,364,277 which describe replacing the standard friction type connector which connects a flat cable to a circuit with a new type of two-part connector. A plurality of projecting interconnection features is provided on a first part of the connector. These projecting features are pressed against similar features or metallic connecting pads on a second part of the connector to form an electrical connection. The two connector parts are then physically clamped together ensuring the electrical contact between the two circuits. U.S. Pat. No. 5,197,184 and U.S. Pat. No. 5,364,277, in addition, relates to the additive electroforming of the plurality of projecting interconnection features. The circuit has an insulating substrate from which raised copper conductive elements protrude. The surface of the copper conductive elements is covered with gold. The techniques for forming and controlling the shape of the plurality of projecting interconnecting features are developed in U.S. Pat. No. 5,307,561 and U.S. Pat. No. 5,354,205. These documents describe how pyramidal and conical projecting features may be formed. The described connectors are available commercially from Packard-Hughes Interconnect under the trademark of "Gold Dot".